The present invention relates to endoscopes of the type which include an elongated ultrasonic transducer, such as a linear transducer or a phased array transducer.
Endoscopes are devices which are used for the visual inspection of internal organs of living bodies. They typically include a tube, which may be flexible or rigid, which extends between a control housing at its proximal end and a tip or probe at its distal end. A bendable tube portion is included adjacent to the probe. The bendable portion is bent under operator control through the use of a control mechanism mounted on the control housing. Optical illuminating and viewing means, which include an objective lens in the probe and an eyepiece in the control housing, are provided. The optical means are used to view the interior surfaces of the body cavities through which the endoscope passes.
While an endoscope provides an operator with information concerning interior surface conditions, the need for ultrasonic imaging of underlying surfaces and interior organs has been recognized, and heretofore, endoscopic probes containing ultrasonic tranducers were known. One such probe was described in U.S. Pat. No. 3,938,502 entitled APPARATUS WITH A CATHETER FOR EXAMINING HOLLOW ORGANS OR BODIES WITH THE ULTRASONIC WAVES which issued on Feb. 17, 1976. That probe, however, lacked optical viewing means. Optical viewing means are needed to permit an operator to position the ultrasonic probe at a desired location within a patient's body. Without knowledge of transducer location and orientation, any ultrasonic image obtained is of minimal diagnostic use. Additionally, optical viewing means are generally required to safely guide a probe as it is inserted into a patient's body, in order to avoid harming the patient.
Endoscopes have heretofore been provided with linear ultrasonic transducer arrays at their distal ends. For example, U.S. Pat. No. 4,273,111 entitled ENDOSCOPE WITH BEND ANGLE CONTROL which issued to T. Tsukaya on June 16, 1981 describes an endoscope with a freely bendable section which includes a number of "supersonic transducers" at its distal end. While such endoscopes are able to provide simultaneous visual and ultrasonic imaging of internal body parts, a problem which has been encountered when such an endoscope is inserted into a body cavity is that the elongated, inflexible section housing the transducer interferes with the operator's ability to move the bendable, distal portion of the endoscope.
One endoscope, which appears in Japanese Pat. No. 55-168309, has a series of circumferentially placed transducers which are set back somewhat from the extreme distal end of the endoscope. The invention described in that patent is primarily concerned with providing an endoscope for producing tomographic images, i.e., images which correspond to slices taken in a plane perpendicular to the longitudinal axis of the body. In particular, the invention described in that patent is an endoscope which has an outlet port through which water can be pumped into the stomach. The purpose of pumping water into the stomach, as described therein, is to displace any gas present in the stomach whereby a better interface match for the ultrasound is provided. That endoscope also includes a relatively wide diameter tip at the distal end of the probe. The wide tip is intended to block the duodenum to prevent water, which is pumped into the stomach, from flowing out into the duodenum.